The role of the substantia nigra on the rage reaction elicited by hypothalamic stimulation,in the cat

Summary The effects of substantia nigra stimulation on the rage reaction evoked by hypothalamic activation were studied. The reference value of the rage reaction was the latency of the hissing, which was constant in all animals when hypothalamic stimulation was performed with the same parameters. Simultaneous activation of substantia nigra and hypothalamus determined a significant decrease in hissing latency. The influence of the substantia nigra on the affective components of the aggressive behavior is underlined.This work was supported by a grant from the Consiglio Nazionale delle Ricerche Roma, Italy.     

Antidromic latency variations of nigral compacta neurones

Summary Variations in the antidromic latency of substantia nigra compacta neurones were commonly observed following striatal stimulation. These results provide electrophysiological evidence for a branched unmyelinated nigrostriatal pathway and demonstrate that the antidromic criterion of constant latency is not valid for this type of pathway.     

Long-term depressor effects of noradrenaline and dopamine neurons transplanted into the third ventricle of the brain of salt-loaded hypertensive rats

Neural tissues including A 6 group noradrenaline neurons in the locus ceruleus or A 10 group dopamine neurons in the substantia nigra were transplanted into the third ventricle at the preoptic-anterior hypothalamic level of rats made hypertensive by salt loading. Either transplant exerted a long-lasting depressor effect.     

Long-term depressor effects of noradrenaline and dopamine neurons transplanted into the third ventricle of the brain of salt-loaded hypertensive rats

Summary Neural tissues including A 6 group noradrenaline neurons in the locus ceruleus or A 10 group dopamine neurons in the substantia nigra were transplanted into the third ventricle at the preoptic-anterior hypothalamic level of rats made hypertensive by salt loading. Either transplant exerted a long-lasting depressor effect.     

Monosynaptic inhibition of thalamic neurons produced by stimulation of the substantia nigra

Summary Electrical stimulation to the substantia nigra (Pars reticulata) produced a monosynaptic inhibition of the neurons of the ventromedial necleus of the thalamus in anesthetized cats.     

Modification of visual signals by nigral stimulation.

Responses of the lateral geniculate neurons to light were modified by stimulation of the substantia nigra. Nigral stimulation often caused enhancement of firing in neurons responding primarily to flash, but it usually had the contrary effect on units inhibited by light.     

Modification of visual signals by nigral stimulation

Summary Responses of the lateral geniculate neurons to light were modified by stimulation of the substantia nigra. Nigral stimulation often caused enhancement of firing in neurons responding primarily to flash, but it usually had the contrary effect on units inhibited by light.     

Long-term depressor effects of catecholamine neuronal grafts in the third ventricle of the brain in normotensive rats

Neuronal tissue containing A-6 group noradrenalin (NA) neurons of the locus ceruleus, or A-10 group dopamine (DA) neurons of the substantia nigra, was grafted into the third ventricle at the level of the preoptic-anterior hypothalamic region, in normotensive male rats. A significant and long-lasting depressor effect was shown in rats with either graft. In rats with an NA neuron-rich graft, plasma concentrations of arginine-vasopressin (AVP), plasma renin activity (PRA), and corticosterone (CS) decreased significantly, whereas in rats with a DA neuron-rich graft, AVP and PRA concentrations also decreased significantly but CS showed no significant change. Neither NA nor adrenalin in plasma changed significantly in rats with either graft.     

Long-term depressor effects of catecholamine neuronal grafts in the third ventricle of the brain in normotensive rats

Summary Neuronal tissue containing A-6 group noradrenalin (NA) neurons of the locus ceruleus, or A-10 group dopamine (DA) neurons of the substantia nigra, was grafted into the third ventricle at the level of the preoptic-anterior hypothalamic region, in normotensive male rats. A significant and long-lasting depressor effect was shown in rats with either graft. In rats with an NA neuron-rich graft, plasma concentrations of arginine-vasopressin (AVP), plasma renin activity (PRA), and corticosterone (CS) decreased significantly, whereas in rats with a DA neuron-rich graft, AVP and PRA concentrations also decreased significantly but CS showed no significant change. Neither NA nor adrenalin in plasma changed significantly in rats with either graft.     

Reciprocal connections between substantia nigra and medullary reticular formation in the rat

Summary Electrophysiological analysis shows reciprocal connections between substantia nigra and medullary reticular formation (nucleus reticularis giganto celullaris). The nigro-reticular connection appears to be monosynaptic, as shown by antidromic activation, and comprises an ipsi and a contralateral component. Its effect is mainly inhibitory. The reticulonigral component produces mainly excitatory effects and includes fibres from nucleus giganto celullaris and nucleus parvocelullaris in the medullary reticular formation.This work was aided by a grant from CONICIT (projecto 31.26.S1-0412).     

Induction of rotational behaviour by intranigral baclofen suggests possible GABA-agonist activity

Summary In rats, unilateral injections of the GABA-derivative baclofen into the zona reticulata of the substantia nigra produced a contralateral rotation that was translated to ipsilateral rotation under the influence of amphetamine. These results mimic those following unilateral elevation of GABA levels in the substantia nigra and suggest that baclofen may have some GABA agonist activity following intracerebral injection.Baclofen was a generous gift of Ciba-Geigy Ltd.J. L. W. is a Medical Research Council Scholar.     

A preliminary study on the behaviour and biochemical responses subsequent to the injection of 5,6-dihydroxy-tryptamine into the substantia nigra of the rat

Summary Injection of 5,7-dihydroxytryptamine into the substantia nigra of rats produces an increase of dopamine in the ipsilateral striatum, and when these animals are injected with amphetamine they do not exhibit any rotation. The mode of action of this neurotoxin is compared with that of 6-hydroxydopamine.     

Projections from nucleus accumbens to globus pallidus and substantia nigra in the rat

Stimulation of nucleus accumbens produces inhibition and facilitation of neuronal activity in the ipsilateral globus pallidus and substantia nigra. Small lesions in the accumbens reduce pallidal but not nigral GABA content.     

A preliminary study on the behaviour and biochemical responses subsequent to the injection of 5,6-dihydroxytryptamine into the substantia nigra of the rat.

Injection of 5,7-dihydroxytryptamine into the substantia nigra of rats produces an increase of dopamine in the ipsilateral striatum, and when these animals are injected with amphetamine they do not exhibit any rotation. The mode of action of this neurotoxin is compared with that of 6-hydroxydopamine.     

Projections from nucleus accumbens to globus pallidus and substantia nigra in the rat

Summary Stimulation of nucleus accumbens produces inhibition and facilitation of neuronal activity in the ipsilateral globus pallidus and substantia nigra. Small lesions in the accumbens reduce pallidal but not nigral GABA content.Acknowledgment. This work was supported by an MRC grant to Prof. D. W. Straughan.     

Application to the study of connections in the CNS of the retrograde axonal transport of an iron-dextran complex]

The retrograde axonal transport of an iron-dextran complex was observed in neurons of the substantia nigra and of the intralaminar nuclei of the thalamus, after previous injection into the striatum. The histochemical demonstration of iron is simple and rapid, and can be combined with that of horseradish peroxidase, under precise conditions in the sequence of reactions. The iron-dextran complex revealed to be a valuable material for neuronal connectivity studies in the central nervous system.     

The smooth endoplasmic reticulum as a possible storage site for dendritic dopamine in substantia nigra neurones.

In dendrites of the substantia nigra neurones the monoamine marker 5-hydroxydopamine injected intracerebrally was localized inside of smooth endoplasmic reticulum cisterns. This observation opens the possibility of the existence of an alternative site for dopamine storage in dendrites as opposed to the well-known vesicular storage.     

Effects of penfluridol of dopamine-sensitive adenylate cyclase in corpus striatum and substantia nigra of rats.

Penfluridol, a neuroleptic with diphenylbutyl piperidine structure, blocked the dopamine-sensitive adenylate cyclase in homogenates of corpus striatum and substantia nigra of rats, probably by a competitive antagonism versus dopamine.     

The action of substance P on mesencephalic reticular and substantia nigral neurones of the rat

Summary Extracellular recordings were made from neurones in the mesencephalic reticular formation and substantia nigra of the rat which was anaesthetized with urethane 1.5–2 g/kg i.p. Out of 44 cells tested 42 were excited by Substance P applied iontophoretically and in some cases this excitation was rapid. Evidence is presented for Substance P as a putative excitatory transmitter onto reticular and nigral neurones possibly released from primary sensory afferents.     

Monoamine oxidase activity in single nerve cell bodies from substantia nigra of rat and man

Summary In single nerve cell bodies isolated from the substantia nigra of man and rat the active forms of MAO A and MAO B were found by the use of the microdiver technique and specific inhibitors.